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| author | Juergen Gross <jgross@suse.com> | 2018-02-01 15:40:19 +0300 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2018-02-06 11:37:18 +0300 |
| commit | 4f277295e54c5b7340e48efea3fc5cc21a2872b7 (patch) | |
| tree | c0afd5986abcc7183cf4253a578e7a732753f7d8 | |
| parent | ddb9e13af3bba3f8c36ccee0eb9563a82b425c12 (diff) | |
| download | linux-4f277295e54c5b7340e48efea3fc5cc21a2872b7.tar.xz | |
x86/xen: init %gs very early to avoid page faults with stack protector
When running as Xen pv guest %gs is initialized some time after
C code is started. Depending on stack protector usage this might be
too late, resulting in page faults.
So setup %gs and MSR_GS_BASE in assembly code already.
Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: Chris Patterson <cjp256@gmail.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
| -rw-r--r-- | arch/x86/xen/xen-head.S | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S index 497cc55a0c16..96f26e026783 100644 --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -9,7 +9,9 @@ #include <asm/boot.h> #include <asm/asm.h> +#include <asm/msr.h> #include <asm/page_types.h> +#include <asm/percpu.h> #include <asm/unwind_hints.h> #include <xen/interface/elfnote.h> @@ -35,6 +37,20 @@ ENTRY(startup_xen) mov %_ASM_SI, xen_start_info mov $init_thread_union+THREAD_SIZE, %_ASM_SP +#ifdef CONFIG_X86_64 + /* Set up %gs. + * + * The base of %gs always points to the bottom of the irqstack + * union. If the stack protector canary is enabled, it is + * located at %gs:40. Note that, on SMP, the boot cpu uses + * init data section till per cpu areas are set up. + */ + movl $MSR_GS_BASE,%ecx + movq $INIT_PER_CPU_VAR(irq_stack_union),%rax + cdq + wrmsr +#endif + jmp xen_start_kernel END(startup_xen) __FINIT |